Sadly, the extraction of best possible audio quality is of interest to perhaps 0.1% of users.
Microsoft is probably aware of this and does not advertise Vista as superior audio platform.
OTOH, your network bandwidth will be arbitrarily throttled if you play back any media on Vista.
"Hey, the design of our network and media systems means that playback might be choppy during network use. I know, instead of fixing those systems, we'll just throttle the network enough that it will never interfere with playback."